Conventional micro-fluid ejection heads, for example, ink jet printheads, have electrical wiring exclusively located on a flexible circuit electrically connected to a substrate or on the substrate itself. In such conventional micro-fluid ejection heads, the substrate contains ejection devices, for example, resistors and piezoelectric device, drivers for the ejection devices, and conductors providing connection between the drivers and the ejection devices. Contact pads are also provided on the substrate to provide electrical communication with a control source, for example, an ink jet printer.
As micro-fluid ejection heads become more complex and include more functionality, the size of the substrate must often be increased to accommodate additional electrical components and/or contact pads and conductive paths required for the electrical components. Also, conductive pathways on the substrate become more complicated as the number of electrical components increases. At the same time, there is a need to increase the number of ejection devices on the substrate and reduce the size of the substrate in order to provide increased operational speed in closer droplet spacing. Accordingly, there continues to be a need for improved micro-fluid ejection heads and construction techniques that enable substrate size reduction and/or increased functionality for a given substrate size.
With regard to the foregoing and other needs, exemplary embodiments of the disclosure provide, for example, a micro-fluid ejection device having a polymeric layer adjacent a substrate, and at least one conductive layer embedded in the polymeric layer. The polymeric layer may be made of at least two layers of polymeric material.
In another aspect, the disclosure provides a method for making a micro-fluid ejection head. According to one such method, a first polymeric material for a polymeric layer is deposited adjacent a substrate. The first polymeric material is imaged and developed. Next a conductive material is deposited adjacent at least a portion of the first polymeric material to provide a conductive path for electrical communication with an electrical signal source. At least a second polymeric material for the polymeric layer is deposited adjacent the first polymeric material and conductive material to provide the conductive path embedded in the polymeric layer.
In yet a further aspect, the disclosure provides a method for reducing a size of a substrate for a micro-fluid ejection head. According to one such method, a first polymeric material for a polymeric layer is deposited adjacent a substrate. The first polymeric material is imaged and developed. An electrical component selected from the group consisting of electrical traces, capacitors, anti-fuse devices, and the like is deposited adjacent the first polymeric material. At least a second polymeric material for the polymeric layer is deposited adjacent the first polymeric material and electrical component to provide the electrical component embedded in the polymeric layer.
An advantage of exemplary methods and apparatus described herein includes that electrical components, such as conductive traces, anti-fuse devices, and capacitors, which traditionally are provided on a substrate, may be provided as an embedded component in multiple polymeric layers adjacent the substrate. When the substrate contains a fluid flow slot therethrough, electrical tracing may cross-over the slot in the polymeric layer rather than being routed around the slot.